In the past solvent cleaners have long been employed using petroleum based solvents. While such solvent cleaners have been efficient, the disposal of the petroleum based solvent has been increasingly difficult with attendant inconvenience and added expense since the solvent has been classified as a hazardous waste material.
To avoid the use of petroleum based solvents, biodegradable detergents in an aqueous solution have been employed. In order to be effective, stationary tanks have been utilized with heating elements to clean industrial and automotive parts and the like. The aqueous solvent, when disposal is needed, does not require the rigorous hazardous waste standards of petroleum based solvents.
While such biodegradable solvent cleaning systems have been efficient, their use of heating equipment has necessitated cumbersome heavy installations that are not readily transportable and make accessibility of individual parts to be cleaned difficult. Other solvent cleaners have also employed screens or cartridge type filters which are messy to clean and dispose of.